The invention concerns a process for the treatment of imprinted wastepaper, as well as arrangements for the performance of the process. Such a process is known from DE-OS 30 40 998. In this process, the soaking is carried out in a drum which is rotatable about a horizontal axis. The soaking process is proposed to be carried out at consistencies of 20 to 40%. Thereafter, the wastepaper is heavily diluted with water, so that another sorting process can be carried out in a drum rotatable about a horizontal axis and equipped with a shell that is provided with screen perforations, the sorting taking place at a consistency between 8 and 12%. The hole sizes there are 4 to 12 mm in diameter.
It has been demonstrated that the removal of printing inks from the fibers can be performed more efficiently if the wastepaper to be processed is prior to the actual dissolution is treated by means of pulper or drum using a solution of chemicals, i.e., that it is quasi "presoaked/preimpregnated."
In this "preimpregnation," the printing ink binders are softened to a point such that the printing ink particles can in the following dissolution process be separated from the fibers more effectively than is the case without "preimpregnation." The preimpregnation is most suitably carried out at a consistency of more than 12%.
The patent document DE 35 22 395 Cl also provides for "presoaking" the wastepaper, stacking it in a reaction tower and dissolving it in the tower base by means of a pulper, where coarse contaminations of the wastepaper, for example plastic foils, pieces of wire and similar, can be continuously removed from the fiber suspension.
This process has the disadvantage that only a slight share of contaminations may be contained in the wastepaper because, e.g., a share higher than 1% (based on otto wastepaper) may lead to bridge formation, clogging etc. in the tower base, the elimination of which is time-consuming and associated with considerable production losses.
The problem underlying the present invention is to perform, in the treatment of wastepaper containing a very high share of paper imprinted with printing inks, the removal of the printing inks very efficiently and effectively. There is to be no further presorting of the wastepaper necessary, so that then all contaminations may proceed into the treatment process. Moreover, the investments in time and chemicals should be relatively favorable.